Before leaving to visit Moscow on Tuesday, Secretary of State Rex Tillerson sent a strong message to Russia in regard to its support for Syrian President Bashar al-Assad.

Speaking with reporters in Lucca, Italy, Secretary Tillerson set forth a clear ultimatum for Russia:

“We want to relieve the suffering of the Syrian people. We want to create a future for Syria that is stable and secure. And so Russia can be a part of that future and play an important role, or Russia can maintain its alliance with this group, which we believe is not going to serve Russia’s interest longer-term. But only Russia can answer that question.”

Additionally, Tillerson shifted some of the blame for Assad's use of chemical weapons onto the Russians.

“It is also clear Russia has failed to uphold the agreements that had been entered into under multiple U.N. Security Council resolutions,” Tillerson said. “These agreements stipulated Russia as the guarantor of a Syria free of chemical weapons, that they would also locate, secure, and destroy all such armaments in Syria.”

Tillerson added one last punch toward Russian involvement in Syria, saying, “It is unclear whether Russia failed to take this obligation seriously or Russia has been incompetent, but this distinction doesn't much matter to the dead.”

Pressed as to why he believes he could be more successful at dissuading Russian support for the Assad regime than his predecessor, John Kerry, Tillerson explained his view.

“Well, I hope that what the Russian Government concludes is that they have aligned themselves with an unreliable partner in Bashar al-Assad,” Tillerson said. “They had signed the chemical weapons accord themselves — the Syrian Government; the Russian Government had signed that accord; and now Assad has made the Russians look not so good under these circumstances.”

With the harsh remarks coming just before Tillerson's scheduled trip to Moscow — and with increasing tensions between the Kremlin and Washington, D.C. — it's currently unclear whether Tillerson will meet with Russian President Vladimir Putin during his visit.